scholarly journals Aiming Strategy on a Prototype-Scale Solar Receiver: Coupling of Tabu Search, Ray-Tracing and Thermal Models

2021 ◽  
Vol 13 (7) ◽  
pp. 3920
Author(s):  
Benjamin Grange ◽  
Gilles Flamant
Keyword(s):  
Tabu Search ◽  
Ray Tracing ◽  
Wall Temperature ◽  
Gradual Increase ◽  
Particle Temperature ◽  
Outlet Temperature ◽  
Operation Conditions ◽  
Start Up ◽  
Fluidized Particle ◽  
Solar Receiver

An aiming point strategy applied to a prototype-scale power tower is analyzed in this paper to define the operation conditions and to preserve the lifetime of the solar receiver developed in the framework of the Next-commercial solar power (CSP) H2020 project. This innovative solar receiver involves the fluidized particle-in-tube concept. The aiming solution is compared to the case without the aiming strategy. Due to the complex tubular geometry of the receiver, results of the Tabu search for the aiming point strategy are combined with a ray-tracing software, and these results are then coupled with a simplified thermal model of the receiver to evaluate its performance. Daily and hourly aiming strategies are compared, and different objective normalized flux distributions are applied to quantify their influence on the receiver wall temperature distribution, thermal efficiency and particle outlet temperature. A gradual increase in the solar incident power on the receiver is analyzed in order to keep a uniform outlet particle temperature during the start-up. Results show that a tradeoff must be respected between wall temperature and particle outlet temperature.

Thermal Performances of a High Temperature Air Solar Absorber Based on Compact Heat Exchange Technology

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
B. Grange ◽  
A. Ferrière ◽  
D. Bellard ◽  
M. Vrinat ◽  
R. Couturier ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Wall Temperature ◽  
Solar Irradiation ◽  
Metallic Surface ◽  
Small Scale ◽  
Maximum Pressure ◽  
Outlet Temperature ◽  
Solar Absorber ◽  
Operation Conditions ◽  
Solar Receiver

In the framework of the French PEGASE project (Production of Electricity by GAs turbine and Solar Energy), CNRS/PROMES laboratory is developing a 4 MWth pressurized air solar receiver with a surface absorber based on a compact heat exchanger technology. The first step of this development consists in designing and testing a pilot scale (1/10 scale, e.g., 360 kWth) solar receiver based on a metallic surface absorber. This paper briefly presents the hydraulic and thermal performances of the innovative pressurized air solar absorber developed in a previous work. The goal is to be capable of preheating pressurized air from 350 °C at the inlet to 750 °C at the outlet, with a maximum pressure drop of 300 mbar. The receiver is a cavity of square aperture 120 cm × 120 cm and 1 m deepness with an average concentration in the aperture of more than 300. The square shaped aperture is chosen due to the small scale of the receiver; indeed, the performances are not enhanced that much with a round aperture, while the manufacturability is much more complicated. However in the perspective of PEGASE, a round aperture is likely to be used. The back of the cavity is covered by modules arranged in two series making the modular and multistage absorber. The thermal performances of one module are considered to simulate the thermal exchange within the receiver and to estimate the energy efficiency of this receiver. The results of the simulation show that the basic design yields an air outlet temperature of 739 °C under design operation conditions (1000 W/m2 solar irradiation, 0.8 kg/s air flow rate). Using the cavity walls as air preheating elements allows increasing the air outlet temperature above 750 °C as well as the energy efficiency up to 81% but at the cost of a critical absorber wall temperature. However, this wall temperature can be controlled by applying an aiming point strategy with the heliostat field.

scholarly journals Efficiency Enhancement on Thermal Comfort Assessment of Indoor Space with Air-Conditioner Using Computational Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Yu-Tuan Chou ◽  
Shao-Yi Hsia ◽  
Bi-Wen Lee
Keyword(s):  
Taguchi Method ◽  
Thermal Comfort ◽  
Flow Simulation ◽  
Successful Implementation ◽  
Outlet Temperature ◽  
Air Conditioner ◽  
Indoor Space ◽  
Factorial Method ◽  
Operation Conditions ◽  
Full Factorial

Thermal comfort providing is one of the biggest uses of energy in building. For giving better human comfort, the suitable operation conditions of air-conditioner are the most important. The quick and right approach is necessary. In this paper, a small office is studied to improve office staff staying for a long period of time and achieve the thermal comfort environment for reducing energy consumption. Commercial software, Solidworks, is utilized for modeling the facilities and the Flow Simulation module for analyzing the air properties of the indoor space. Four types of air-conditioner operation are applied to set the simulated conditions, including exterior temperature, outlet temperature and wind speed of air-conditioner, and location of air-conditioner. Predicted mean vote (PMV) and predicted percent dissatisfied (PPD) at specific office areas are further acquired through dynamic anthropometry. For seeking the optimal control factors, both of the full factorial method and Taguchi method are utilized to obtain the PMV of specified location. The analyzed result shows the evaluation speed of indoor thermal comfort by Taguchi method is faster than the full-factorial method. It is concluded that software simulation with Taguchi method shows the successful implementation and higher efficiency for thermal comfort assessment.

scholarly journals Structural Analysis of a Direct Heated Tubular Solar Receiver for Supercritical CO2 Brayton Cycle

2015 ◽  
Author(s):  
Jesus D. Ortega ◽  
Joshua M. Christian ◽  
Clifford K. Ho
Keyword(s):  
Thermal Stresses ◽  
Structural Model ◽  
Structural Integrity ◽  
Permanent Deformation ◽  
Creep Model ◽  
Outlet Temperature ◽  
Ansys Fluent ◽  
Future Design ◽  
Pressure Load ◽  
Solar Receiver

Closed-loop super-critical carbon dioxide (sCO2) Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. However, high temperatures (650–700°C) and pressures (20–25 MPa) are required in the solar receiver. In this study, an extensive material review was performed along with a tube size optimization following the ASME Boiler and Pressure Vessel Code and B31.1 and B313.3 codes respectively. Subsequently, a thermal-structural model was developed using ANSYS Fluent and Structural to design and analyze the tubular receiver that could provide the heat input for a ∼2 MWth plant. The receiver will be required to provide an outlet temperature of 650°C (at 25 MPa) or 700°C (at 20 MPa). The induced thermal stresses were applied using a temperature gradient throughout the tube while a constant pressure load was applied on the inner wall. The resulting stresses have been validated analytically using constant surface temperatures. The cyclic loading analysis was performed using the Larson-Miller creep model in nCode Design Life to define the structural integrity of the receiver over the desired lifetime of ∼10,000 cycles. The results have shown that the stresses induced by the thermal and pressure load can be withstood by the tubes selected. The creep-fatigue analysis displayed the damage accumulation due to the cycling and the permanent deformation of the tubes. Nonetheless, they are able to support the required lifetime. As a result, a complete model to verify the structural integrity and thermal performance of a high temperature and pressure receiver has been developed. This work will serve as reference for future design and evaluation of future direct and indirect tubular receivers.

scholarly journals Emission characteristics and vapour/particulate phase distributions of PCDD/F in a hazardous waste incinerator under transient conditions

2018 ◽  
Vol 5 (1) ◽  
pp. 171079 ◽  
Author(s):  
Min Li ◽  
Chao Wang ◽  
Kefa Cen ◽  
Mingjiang Ni ◽  
Xiaodong Li
Keyword(s):  
Polychlorinated Biphenyl ◽  
Vapour Phase ◽  
Emission Characteristics ◽  
Waste Incinerator ◽  
Particulate Phase ◽  
Linear Distribution ◽  
Transient Conditions ◽  
Operation Conditions ◽  
Start Up ◽  
Stack Gas

Polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) emission characteristics and vapour/particulate phase partitions under three continued operation conditions, i.e. shut-down, start-up and after start-up, were investigated by sampling stack gas. The results indicated that the PCDD/F emission levels were 0.40–18.03 ng I-TEQ Nm −3 , much higher than the annual monitoring level (0.016 ng I-TEQ Nm −3 ). Additionally, the PCDD/F emission levels in start-up were higher than the other two conditions. Furthermore, the PCDD/F congener profiles differed markedly between shut-down and start-up, and the chlorination degree of PCDD/F increased in shut-down and decreased evidently in start-up. Moreover, PCDD/F vapour/particulate phase distributions varied significantly under three transient conditions. The PCDD/F vapour phase proportion decreased as the shut-down process continued, then increased as the start-up process proceeded, finally more than 98% of the PCDD/F congeners were distributed in the vapour phase after start-up. The correlations between log( C v / C s ) versus log  p L 0 of each PCDD/F congener in stack gas were disorganized in shut-down, and trend to a linear distribution after start-up. Besides, polychlorinated biphenyl emissions show behaviour similar to that of PCDD/F, and the lower chlorinated congeners have a stronger relationship with 2,3,7,8-PCDD/Fs, such as M1CB and D2CB.

Coupled Fluid Flow and Radiation Modeling of a Cylindrical Small Particle Solar Receiver

2012 ◽  
Author(s):  
Adam Crocker ◽  
Fletcher Miller
Keyword(s):  
Cylinder Wall ◽  
Outlet Temperature ◽  
Gas Temperature ◽  
Dynamics Modeling ◽  
Ansys Fluent ◽  
Data Output ◽  
Gaussian Fit ◽  
Radiation Modeling ◽  
Solar Receiver ◽  
Initial Results

This research expands on previous work by coupling the in-house Monte Carlo Ray Trace (MCRT) radiation model with the more sophisticated fluid dynamics modeling capabilities of ANSYS FLUENT. This allows for the inclusion of more realistic inlet and outlet geometries in the receiver, as well as a turbulence model and much finer grid sizing. Taken together, these features give a more complete picture of the heat transfer, mixing, and temperature profiles within the receiver than previous models. This flow solution is coupled to the MCRT code, by using the in-house MCRT radiation solver to provide the source term of the energy equation. The temperature data output from FLUENT is then fed back into the FORTRAN MCRT code, via a User Defined Function written in C#, and the two models iterate until convergence. The solar input has been modified from the previous model to provide a Gaussian fit to a calculated flux distribution, which is more realistic than a uniform flux. Initial results for a 5 MW solar input agree with the trend identified in Ruther’s work regarding the influence of particle mass loading on heating in the receiver. The maximum outlet temperature reached is 1430K, which is on target for driving a Brayton cycle gas turbine. Cylinder wall temperatures are consistently below those of the gas boundary layer, and significantly below the maximum gas temperature in the receiver cavity.

scholarly journals Gas-Solid Flow in a Fluidized-Particle Tubular Solar Receiver: Off-Sun Experimental Flow Regimes Characterization

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7392
Author(s):  
Ronny Gueguen ◽  
Guillaume Sahuquet ◽  
Samuel Mer ◽  
Adrien Toutant ◽  
Françoise Bataille ◽  
...  
Keyword(s):  
Acquisition Time ◽  
Internal Diameter ◽  
Short Acquisition Time ◽  
Wide Range ◽  
Temporal Pressure ◽  
Secondary Air ◽  
Fluidized Particle ◽  
Solar Power Tower ◽  
Fluidized Particles ◽  
Solar Receiver

The fluidized particle-in-tube solar receiver concept is promoted as an attractive solution for heating particles at high temperature in the context of the next generation of solar power tower. Similar to most existing central solar receivers, the irradiated part of the system, the absorber, is composed of tubes in which circulate the fluidized particles. In this concept, the bottom tip of the tubes is immersed in a fluidized bed generated in a vessel named the dispenser. A secondary air injection, called aeration, is added at the bottom of the tube to stabilize the flow. Contrary to risers, the particle mass flow rate is controlled by a combination of the overpressure in the dispenser and the aeration air velocity in the tube. This is an originality of the system that justifies a specific study of the fluidization regimes in a wide range of operating parameters. Moreover, due to the high value of the aspect ratio, the particle flow structure varies along the tube. Experiments were conducted with Geldart Group A particles at ambient temperature with a 0.045 m internal diameter and 3 m long tube. Various temporal pressure signal processing methods, applied in the case of classical risers, are applied. Over a short acquisition time, a cross-reference of the results is necessary to identify and characterize the fluidization regimes. Bubbling, slugging, turbulent and fast fluidization regimes are encountered and the two operation modes, without and with particle circulation, are compared.

scholarly journals Hybrid Nonlinear MPC of a Solar Cooling Plant

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2723 ◽  
Author(s):  
Eduardo F. Camacho ◽  
Antonio J. Gallego ◽  
Juan M. Escaño ◽  
Adolfo J. Sánchez
Keyword(s):  
Control Strategy ◽  
Air Conditioning ◽  
Operation Mode ◽  
Outlet Temperature ◽  
Continuous Variables ◽  
Solar Cooling ◽  
Operation Conditions ◽  
Predictive Controller ◽  
Solar Field ◽  
Layer Control

Solar energy for cooling systems has been widely used to fulfill the growing air conditioning demand. The advantage of this approach is based on the fact that the need of air conditioning is usually well correlated to solar radiation. These kinds of plants can work in different operation modes resulting on a hybrid system. The control approaches designed for this kind of plant have usually a twofold goal: (a) regulating the outlet temperature of the solar collector field and (b) choosing the operation mode. Since the operation mode is defined by a set of valve positions (discrete variables), the overall control problem is a nonlinear optimization problem which involves discrete and continuous variables. This problems are difficult to solve within the normal sampling times for control purposes (around 20–30 s). In this paper, a two layer control strategy is proposed. The first layer is a nonlinear model predictive controller for regulating the outlet temperature of the solar field. The second layer is a fuzzy algorithm which selects the adequate operation mode for the plant taken into account the operation conditions. The control strategy is tested on a model of the plant showing a proper performance.

scholarly journals First On-Sun Tests of a Centrifugal Particle Receiver System

2018 ◽  
Author(s):  
Miriam Ebert ◽  
Lars Amsbeck ◽  
Reiner Buck ◽  
Jens Rheinländer ◽  
Bärbel Schlögl-Knothe ◽  
...  
Keyword(s):  
Transport System ◽  
Cooling System ◽  
Particle Temperature ◽  
Thermal Power ◽  
Air Cooling ◽  
Outlet Temperature ◽  
Receiver Design ◽  
Test Setup ◽  
Receiver System ◽  
Bucket Elevator

One direct absorption receiver concept currently investigated at the DLR is the Centrifugal Particle Receiver (CentRec®). Successful tests and promising results of this receiver design have been achieved in a Proof-of-Concept scale with 7.5 kW thermal power and 900°C particle temperature in 2014. Based on these results the prototype has been scaled up to 2.5 MW thermal power for a future pilot plant. Lab tests have been carried out with infrared heaters. In a next step the prototype has been prepared to be tested on-sun in a test setup in the Juelich Solar Tower, Germany. The tests aim to demonstrate high temperature operation and to evaluate the performance of the system. The test setup consists of a centrifugal receiver integrated into the tower and a closed loop particle transport system. The transport system includes an air cooling system to cool down the particles at the receiver outlet, cold particle storage, belt bucket elevator, hopper and particle metering system. While the 2.5 MWth receiver prototype has been developed in a former project, the further infrastructure for the on-sun tests needed to be designed, manufactured and installed. The system is equipped with measurement instrumentation, data acquisition system and control software. Manufacturing of all main components has been completed. Installation of the test setup started in November 2016 and finished in June 2017. Cold and hot commissioning have been carried out from July 2017 until September 2017. On-sun tests started in September 2017. Receiver tests up to 775°C/1,430°F receiver outlet temperature and more than 900°C/1,650°F particle temperature in the receiver have already been achieved. Tests up to 900°C particle outlet temperature are planned at different load levels and will be conducted until summer 2018. This paper describes the test setup for a centrifugal particle receiver system, presenting design, installation and commissioning of the system. It presents test results of first on-sun tests and gives an outlook on further steps regarding solar tests planned for 2018.

Optimization of operation conditions for the start-up of a pilot-scale anaerobic biofilm digester treating leachate

2017 ◽  
Vol 86 ◽  
pp. 43-50 ◽  
Author(s):  
Y Arij ◽  
S. Fatihah ◽  
A.R. Rakmi ◽  
Y. Sarifah
Keyword(s):  
Pilot Scale ◽  
Operation Conditions ◽  
Start Up
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